Wal-Mart (NYSE: WMT) keeps trying to solve the digital download conundrum ... The latest effort: $0.94 DRM-free, 256-kbps MP3 downloads from Universal and EMI with albums priced at $9.22—considerably lower than Apple’s iTunes Plus $1.29 per track. Wal-Mart is playing up the compatibility across players since MP3 can be played on even proprietary players like iPod and Zune. The new catalog includes “hundreds of thousands” of songs and albums” and will be “continually expanded” with major label and indie content.

-- Wal-Mart will continue to sell 128 kbps WMA-format downloads at $0.88. 

-- As a promo, Wal-Mart is selling some albums in MP3 for $7.99.

-- In another sign that Wal-Mart is trying to appeal across formats, the download store is still optimized for IE but has a note saying a Firefox upgrade is in the works.

FT: Wal-Mart’s move is expected to be followed imminently by Amazon. Both retailers already operate video download services on their websites, but their move into music downloading has been delayed by the debate with music studios over the implications of the DRM-free system.

Update: In a note by Rich Greenfield of Pali Research, he says that Wal-Mart’s entry into the sale of DRM-free music could signal a more rapid decline in album pricing, with CDs likely to lose even more shelf-space at physical retail as a result...this leads us to believe that 2008 CD declines are likely to be far more severe than the 18%-plus declines experienced year-to-date in 2007. “We suspect the impact on singles will be more muted as iTunes sell singles for $0.99, while Wal-mart sells MP3 singles for $0.94 - we doubt $0.05 is enough for someone to give up the simplicity of a unified service like iTunes if they are using an iPod. The album pricing differential appears to be far more relevant to the music industry near-term.”

• Universal Music Group To Trial DRM-Free Music; iTunes Not Included
• Interview, Kevin Swint, Divisional Merchandise Manager, Digital Media, Wal-Mart